Paper Title
Development of Mathematical Problem-Solving Ability of Grade 8 Students by Using SSCS and Concrete Pictorial Abstract: CPA

Abstract
This research aimed to develop the mathematical problem-solving abilities of grade 8 students by implementing the SSCS instructional model in combination with the Concrete-Pictorial-Abstract (CPA) approach, with a success criterion of 70%. The target group consisted of 30 grade 8 students during the first term of the 2024 academic year at Sarakhampittayakhom School. The research instruments used in this study consist of: 1) 12 lesson plans based on the SSCS instructional model combined with the Concrete-Pictorial-Abstract (CPA) approach, focusing on congruence for grade 8 students. 2) A mathematical problem-solving ability test, consisting of three sets of subjective questions, each with four items. 3) An observation checklist for assessing problem-solving behaviors. This study uses an action research methodology, consisting of three research cycles. The statistical methods used for data analysis include mean, percentage, and standard deviation. The research findings revealed that 16 students (53.33%) achieved the 70% proficiency threshold in the first cycle, with an average score of 20.60. In the second cycle, 20 students (66.67%) met the threshold, with an average score of 22.33. In the third cycle, 25 students (83.33%) surpassed the threshold, with an average score of 25.93. Keywords - Mathematical problem-solving ability, SSCS instructional model, Concrete-Pictorial-Abstract (CPA) approach.